Radiation-sensitive polyimide precursor composition derived from a diaryl fluoronated diamine compound

ABSTRACT

A radiation-sensitive polyimide precursor composition, comprising a polymer of the formula ##STR1## wherein n is a positive integer corresponding to the number of units in the polymer and is sufficiently large to provide the polymer with a number average molecular weight of about 1500-15,000 as determined by vapor pressure osmometry, and wherein for any particular unit in the polymer:→denotes isomerism; 
     R 1  is a tetravalent aromatic non-halogen containing organic radical containing at least one ring of six carbon atoms, said ring characterized by benzenoid unsaturation, the four carbonyl groups being attached directly to separate carbon atoms in a ring of the R 1  radical; 
     R 2  and R 3  are selected from the group consisting of a hydrogen radical and any organic radical containing a photopolymerizable olefinic double bond, at least one of R 2  and R 3  being said organic radical; 
     R 4  and R 5  are selected from the group consisting of perfluoro and perhalofluoro aliphatic hydrocarbons having 1 to 8 carbons; and A and A&#39; are selected from the group consisting of H, Cl, Br, and NO 2 .

BACKGROUND OF THE INVENTION

This invention relates to a radiation-sensitive or photopolymerizablepolyimide precursor composition derived from a diaryl fluoronateddiamine compound that is useful for forming relief structures onelectrical or electronic devices such as semiconductors, capacitors andprinted circuits.

Photopolymerizable polymeric compositions used to form relief structureson electronic devices are well known as shown in, for example: U.S. Pat.No. 3,953,877, issued Apr. 27, 1976, to Sigusch et al.; U.S. Pat. No.3,957,512, issued May 18, 1976, to Kleeburg; and U.S. Pat. No.4,040,831, issued Aug. 9, 1977, to Rubner et al. (now U.S. Pat. No. Re.30,186, reiussed Jan. 8, 1980). Copending U.S. Application Ser. No.336,765, filed Jan. 4, 1982 now abandoned, discloses aradiation-sensitive polyimide precursor composition derived from adiaryl fluoro dianhydride, especially2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride.

The present invention provides for a novel radiation-sensitive polyimideprecursor composition derived from a diaryl fluoronated diamine.

SUMMARY OF THE INVENTION

A radiation-sensitive polyimide precursor composition comprises:

1. a polymer of the formula ##STR2## wherein n is a positive integercorresponding to the number of units in the polymer and is sufficientlylarge to provide the polymer with a number average molecular weight ofabout 1500-15,000 as determined by vapor pressure osmometry, and whereinfor any particular unit in the polymer: → denotes isomerism;

R¹ is a tetravalent, aromatic, non-halogen containing, organic radicalcontaining at least one ring of six carbon atoms, said ringcharacterized by benzenoid unsaturation, the four carbonyl groups beingattached directly to separate carbon atoms in a ring of the R¹ radical;

R² and R³ are selected from the group consisting of a hydrogen radicaland any organic radical containing a photopolymerizable olefinic doublebond, at least one of R² and R³ being said organic radical;

R⁴ and R⁵ are selected from the group consisting of perfluoro andperhalofluoro aliphatic hydrocarbon having 1 to 8 carbons; and A and A'are selected from the group consisting of H, Cl, Br, and NO₂ ;

2. a radiation sensitive polymerizable polyfunctional acrylate compound;and

3. a photopolymerization initiator system comprising hydrogen donorinitiator and aromatic biimidazole.

DETAILED DESCRIPTION OF THE INVENTION

The radiation-sensitive polyimide precursor composition of the presentinvention is useful to form relief structures on electrical orelectronic devices such as capacitors and semiconductors. A solution ofthe composition is applied to a substrate such as a silicon wafer anddried to form a film on the substrate. The film is then exposed toradiation through a masking template (pattern) and photopolymerized. Theunexposed and unpolymerized part of the film is dissolved off with adeveloper solution to form a relief structure. The resulting reliefstructure is baked to eliminate the photopolymerized material and toform a polyimide structure with a sharp definition and with goodmechanical chemical, and electrical properties.

A radiation-sensitive polyimide precursor composition of the presentinvention comprises:

a. a polymer of the formula ##STR3## wherein n is a positive integercorresponding to the number of units in the polymer and is sufficientlylarge to provide the polymer with a number average molecular weight ofabout 1500-15,000 as determined by vapor pressure osmometry, and whereinfor any particular unit in the polymer: → denotes isomerism;

R¹ is a tetravalent, aromatic, non-halogen containing, organic radicalcontaining at least one ring of six carbon atoms, said ringcharacterized by benzenoid unsaturation, the four carbonyl groups beingattached directly to separate carbon atoms in a ring of the R¹ radical;

R² and R³ are selected from the group consisting of a hydrogen radicaland any organic radical containing a photopolymerizable olefinic doublebond, at least one of R² and R³ being said organic radical;

R⁴ and R⁵ are selected from the group consisting of perfluoro andperhalofluoro aliphatic hydrocarbon having 1 to 8 carbons; and A and A'are selected from the group consisting of H, Cl, Br, and NO₂ ;

2. a radiation sensitive polymerizable polyfunctional acrylate compound;and

3. a photopolymerization initiator system comprising hydrogen donorinitiator and aromatic biimidazole.

In the above-described polymer wherein R⁴ and R⁵ are selected from thegroup consisting of perfluoro and perhalofluoro aliphatic hydrocarbonshaving 1 to 8 carbons, perfluoro and perhalofluoro designate materialswhich do not contain hydrogen. Instead, the hydrogen is substitutedtotally by fluorine (perfluoro) or at least 1 fluorine and anotherhalogen (perhalofluoro). In a preferred composition of the presentinvention, R⁴ and R⁵ are selected from the group consisting of --CF₃,--CClF₂ and --CBrF₂. Of particular interest, R⁴ and R⁵ are --CF₃.

The polymer may be prepared by one of at least two methods.

One method involves preparing the addition product of an olefinicallyunsaturated monoepoxide on a product obtained by reacting atetracarboxylic acid dianhydride with at least one organic diaminehaving the structural formula ##STR4## wherein R⁴ and R⁵ are selectedfrom the group consisting of perfluoro and perhalofluoro aliphatichydrocarbons having 1 to 8 carbons; and

A and A' are selected from the group consisting of H, Cl, Br, and NO₂.

The organic diamines preferably utilized in the reaction productdescribed above may be prepared in the manner detailed in U.S. Pat. No.3,310,573, issued Mar. 21, 1967, to Coe; said patent being herebyincorporated by reference into the present disclosure. Particulardiamines of interest include:

4,4'-(hexafluoroisopropylidene)-dianiline;

4,4'-(hexafluoroisopropylidene)-bis(2,6-dibromoaniline);

4,4'-(hexafluoroisopropylidene)-bis(2-nitroaniline);

4,4'-(hexafluoroisopropylidene)-bis(o-phenylene diamine);

4,4'-(hexafluoroisopropylidene)-bis(2-aminotoluene);

4,4'-(hexafluoroisopropylidene)-bis(aminobenzoic acid);

4,4'-(hexafluoroisopropylidene)-bis(2,6-dichloroaniline);

4,4'-(hexafluoroisopropylidene)-bis(N-methylaniline);

4,4'-(hexafluoroisopropylidene)-bis(N-ethylaniline);

4,4'-(hexafluoroisopropylidene)-bis(N-2-cyanoethylaniline);

4,4'-(hexafluoroisopropylidene)-bis(2-nitro-6-chloroaniline);

4,4'-(chloropentafluoroisopropylidene)dianiline;

4,4'-(chloropentafluoroisopropylidene)-bis(2,6-dibromoaniline);

4,4'-(chloropentafluoroisopropylidene)-bis(N,2-cyanoethylaniline);

4,4'-(chloropentafluoroisopropylidene)-bis(2-aminotoluene);

4,4'-(1,3-dichlorotetrafluoroisopropylidene) dianiline;

4,4'-(1,3-dichlorotetrafluoroisopropylidene)-bis(2-aminotoluene).

Tetracarboxylic acid dianhydrides suitable for this invention arecharacterized by the following formula ##STR5## wherein R¹ is atetravalent, aromatic, non-halogen containing, organic radicalcontaining at least one ring of six carbon atoms, said ringcharacterized by benzenoid unsaturation, the four carbonyl groups beingattached directly to separate carbon atoms in a ring of the R¹ radical,and wherein each pair of carbonyl groups is directly attached toadjacent carbon atoms in the R¹ group to provide a 5-membered ring asfollows: ##STR6## Illustrations of dianhydrides suitable for use in thepresent invention include: pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3',-4,4'-diphenyl tetracarboxylicdianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride,2,2',3,3'-diphenyl tetracarboxylic dianhydride,2,2-bis(3,4-dicarboxyphenyl) propane dianhydride,bis(3,4-dicarboxyphenyl) sulfone dianhydride, perylene,3,4,9,10-tetracarboxylic acid dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride,2,2-bis(2,3-dicarboxyphenyl) propane dianhydride,1,1-bis(2,3-dicarboxyphenyl) ethane dianhydride,1,1-bis(3,4-dicarboxyphenyl) ethane dianhydride,bis(2,3-dicarboxyphenyl) methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride,pyrazine-2,3,5,6-tetracarboxylic dianhydride,thiophene,2,3,4,5-tetracarboxylic dianhydride, 3,4,3',4'-benzophenonetetracarboxylic dianhydride.

For the purpose of this invention, it is intended that thetetracarboxylic acid dianhydride be non-halogen containing, therebyexcluding those fluoronated dianhydrides disclosed in copending U.S.application Ser. No. 336,765 filed Jan. 4, 1982 now abandoned.

Any suitable solvent for reacting the tetracarboxylic acid dianhydridewith the diamine may be used. Such suitable solvents are those organicsolvents whose functional groups do not react with either thedianhydride or diamine to a greater extent than the latter do with eachother. Besides being inert to the system and, preferable, being asolvent for the product, the organic solvent must be a solvent for atleast one of the reactants (dianhydride or diamine), preferably for bothof the reactants. A more detailed description of such suitable solventsmay be found in U.S. Pat. Nos. 3,179,614 and 3,179,634, both issued Apr.20, 1965 to Edwards, and U.S. Pat. No. 3,959,350, issued May 25, 1976 toRogers, these three patents being incorporated by reference into thepresent disclosure.

The suitable conditions for reacting the dianhydride and diamine arealso disclosed in detail in the Edwards patents and the Rogers patent.

As noted above, an olefinically unsaturated monoepoxide is added ontothe reaction product prepared from the dianhydride and diamine. Suchmonoepoxides have the formula ##STR7## wherein R⁷ is an olefinicallyunsaturated radical, preferably containing a (meth)acrylicester-containing group.

Preferred olefinically unsaturated monoepoxides are the unsaturatedepoxides glycidyl acrylate and glycidal methacrylate.

Preferably, a composition of the addition product in a solvent for thedianhydride/diamine reaction, will contain about 10-50% by weight, basedon the combined weight of the addition product and solvent, of theaddition product and about 50-90% by weight of the solvent.

In preparing the addition product of the monoepoxide on adianhydride/diamine reaction product, it is advantageous to bring thedianhydride/diamine reaction product (a polyamic acid) to reaction withhydroxyethyl acrylate, hydroxyethyl methacrylate, or a combination ofthe two prior to the reaction with the olefinically unsaturatedmonoepoxide. In this manner, the end-position acid anhydride groups areintercepted or bound, and compounds with a clearly defined structure areobtained. The solubility also can be influenced by means of thisintercept reagent, and, particularly, photosensitivity of the additionproduct is enhanced due to the unsaturated nature of this interceptreagent.

A second method for preparing the polymer comprising the presentinvention is disclosed in the aforementioned Rubner U.S. Pat. No. Re.30,186; said reissue patent being herein incorporated by reference. TheRubner method involves esterifying an aromatic polycarboxylic acidanhydride with a hydroxy alkyl acrylate or methacrylate, then convertingthat esterification product to a corresponding acid chloride derivative,and finally reacting said acid chloride derivative with diamine. In thepresent invention, the aromatic polycarboxylic acid anhydrides are thetetracarboxylic said dianhydrides described above, the diamine has thestructural formula ##STR8## wherein R⁴, R⁵, A and A' are as definedearlier.

Typical hydroxy alkyl acrylates and methacrylates are as follows:hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxy butyl acrylate,hydroxy ethyl methacrylate, hydroxypropyl methacrylate, hydroxybutylmethacrylate and the like.

Thionyl chloride typically may be used to convert the esterificationproduct to a corresponding acid chloride.

Typical solvents in which the esterification of the dianhydride andsubsequent reaction of the acid chloride derivative with diamine cantake place, include butyrolactone, tetrahydrofuran, hexamethylphosphoricacid triamide, and combinations of the above. Other suitable solventsinclude those disclosed in the two Edwards and the Rogers patents andwhich do not react with the thionyl chloride or any other reagent usedto form the acid chloride derivative.

The conditions for effecting such reactions are well-known, and areexemplified in the examples of the Rubner reissue patent.

To reduce radiation exposure time and increase the rate ofphotopolymerization of a polymer product of the type described above andprepared by any method, a photopolymerizable polyimide precursorcomposition of the present invention also comprises:

1. about 5-30% by weight, based on the weight of the polymer product, ofa radiation sensitive polymerizable polyfunctional acrylate compound;and

2. about 0.5-20% by weight, based on the weight of the polymer product,of a photopolymerization initiator system comprising hydrogen donorinitiator and aromatic biimidazole.

Typically useful radiation sensitive polymerizable polyfunctionalacrylate compounds are as follows: trimethylol propane trimethacrylate,trimethylol propane triacrylate, trimethylol propane ethoxylatetrimethacrylate, trimethylol propane ethoxylate triacrylate, trimethylolpropane polyethoxylate trimethacrylate, trimethylol propanepolyethoxylate triacrylate and mixtures thereof. Preferred aretrimethylol propane polyethoxylate triacrylate having a weight averagemolecular weight of about 500-1500 and trimethylol propane ethoxylatetriacrylate, pentaerythritol triacrylate, polyethylene glycoldiacrylate, triethylene glycol diacrylate, polyethylene glycoldimethacrylate, polymethylene diacrylate, polyethylene dimethacrylate,trimethylene glycol dimethacrylate, tetraethylene glycol diacrylate.

It is possible to photopolymerize the composition without the use of theabove polymerizable polyfunctional acrylate compounds in thecomposition. For most practical commercial processes, the presence ofthe polyfunctional acrylate compounds is highly preferred, as it reducesphotopolymerization time.

All molecular weights made reference to herein are determined by vaporpressure osmometry.

Typical aromatic biimidazole photopolymerization initiators aredisclosed by Chambers U.S. Pat. No. 3,479,185 issued Nov. 18, 1969 andCescon U.S. Pat. No. 3,784,557 issued Jan. 9, 1974 which are herebyincorporated by reference. A 2,4,5-triphenyl imidazolyl dimer having anortho substituent on the 2 phenyl ring is a particularly usefulinitiator. Typical initiators of this type are2-o-chlorophenyl-4,5-diphenyl imidazolyl dimer,2-(o-fluorophenyl)-4,5-diphenyl imidazolyl dimer,2-(o-methoxyphenyl)-4,5-diphenyl imidazolyl dimer and mixtures thereof.Particularly preferred are bis(2-o-chlorophenyl-4,5-diphenyl imidazolyl)and bis[2-o-chlorophenyl 4,5-di(m-methoxy phenyl) imidazolyl] sincethese initiators are stable and are excellent photopolymerizationinitiators.

Also hexaaryl biimidazoles can be used as photopolymerization initiatorsas shown in Fishman U.S. Pat. No. 3,552,973 issued Jan. 5, 1971.

Typically useful hydrogen donors, photosensitizers and photoinitiatorsinclude the following: aromatic ketones such as benzophenone, Michler'sketone [4,4'-bis(dimethylamino)benzophenone],4,4'-bis(diethylamino)benzophenone,4-acryloxy-4'-diethylaminobenzophenone,4-methoxy-4'-dimethylaminobenzophenone, 2-ethylanthraquinone,phenanthraquinone, 2-t-butylanthraquinone, 1,2-benzanthraquinone,2,3-benzanthraquinone, 2,3-dichloronaphthoquinone, benzil dimethylketal, and other aromatic ketones such as disclosed in theaforementioned U.S. Pat. No. 3,552,973; benzoin, benzoin ethers such asbenzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, andbenzoin phenyl ether, methylbenzoin, ethylbenzoin and other benzoins,mercaptobenzothiazole, mercaptobenzoxazoles as disclosed in U.S. Pat.No. 4,291,115 and n-phenyl glycine.

It is possible to use combinations of both photosensitizer andphotopolymerization initiators. Generally, the photopolymerization timeis longer if the photosensitizer is not added. As thephotopolymerization is enhanced by the addition of photosensitizers,photoinitiators, or mixtures thereof, it is preferred that suchcompounds be used in the composition in amounts of about 0.1 to 15% byweight, of the composition.

It may be desirable to have a compound present that changes color whenpolymerization is complete, that is a hydrogen donor that provides arapid start for polymerization, and that is a chain transfer agent.Leuco dyes can be used such as those disclosed in the aforementionedU.S. Pat. No. 3,552,973 col. 6, line 6, to col. 11, line 9, whichdisclosure is hereby incorporated by reference. Typically useful dyesare alkyl aminoaromatic alkanes such as tris(diethylamino-o-tolyl)methane, tris(dimethylamino-o-oxylyl) methane and tris(dipropylamino-o-tolyl) methane.

Plasticizers can also be added to the composition of the presentinvention in amounts of 0.1-10% by weight, based on the weight of thepolymer product. Typical plasticizers are tricresyl phosphate, dioctylphthalate, dihexyl phthalate, dinonyl phthalate, polyethylene glycolethers, ethylene glycol dicaprolate.

In the process for applying the composition to substrates, thecomposition is applied and then dried to form a film at about 30°-100°C. for about 20 minutes to 5 hours, depending upon the coatingthickness. The film is then exposed to actinic radiation through apattern for about 1 second to 5 minutes. Preferably, for a commercialprocess exposure times of 1-60 seconds are required and usually anexposure time under 30 seconds is much preferred. Typical radiationsources used are ultraviolet lamps providing a wave length of 250 to 400nanometers and an intensity of 0.5-60 milliwatts per square centimeter(mW/cm²). After exposure, the film is then dipped or sprayed, with adeveloper solution. Typical developer solutions are4-butyrolactone/toluene in a weight ratio from 2/1 to 1/4, dimethylformamide/ethanol in a weight ratio from 2/1 to 1/4.

The film is then washed with a nonsolvent and afterwards, dried. Thefilm is cured to a polyimide relief structure by baking at about150°-450° C. for about 20 minutes to 4 hours. During curing, theacrylate components are decomposed leaving a formed polyimide structure.The resulting relief structure has a sharp definition, as well as goodchemical, electrical and mechanical properties.

Typical uses for the composition are as follows: protective coatings forsemiconductors, dielectric layers for multilayer integrated circuits,high temperature solder mask, bonding multilayer circuits, a finalpassivating coating on electrical electronic devices and the like.

The following example illustrates the invention. All parts andpercentages are on a weight basis, unless otherwise specified, andmolecular weights are determined by vapor pressure osmometry.

EXAMPLE Composition A (Polymer Product)

To a stirred solution of 16.35 grams (0.075 mol) of1,2,4,5-benzenetetracarboxylic anhydride in 115 milliliters ofdimethylacetamide, 18.70 grams (0.056 mol) of4,4'-(hexafluoroisopropylidene)-dianiline added in about 2-gram lotssuch that the internal reaction temperature did not exceed 35° C. Thismixture was then stirred at room temperature for 2 hours, after which0.5 grams (0.004 mol) of hydroxyethyl methacrylate was added and themixture stirred at room temperature for 2 more hours.

Then, 37.5 milliliters of glycidyl methacrylate (GMA), 0.4 grams ofbenzyldimethylamine, and 0.03 grams of hydroquinone were added in thatorder. The mixture was then warmed to between about 50° and 60° C. andstirred for 15 hours.

The reaction solution was then cooled to room temperature and washedwith 5×50 milliliters of petroleum ether to remove unreacted GMA. Thepolymer product was isolated by the dropwise addition of the reactionsolution into 1,000 milliliters of a blend of aromatic hydrocarbons(such as is sold by Union Oil Chemical Division as "Super High FlashNaphtha H-596") accompanied by vigirous stirring. The resultinggelatinous precipitate was triturated with 2×500 milliliters ofpetroleum ether and suction filtered to yield the product as a whitesolid (Composition A).

Composition B

A photopolymerizable polyimide precursor composition of the presentinvention was prepared by charging the following constituents into acontainer and placing the container on a roller where it was mixed for 2hours:

    ______________________________________                                        Ingredient              Amount                                                ______________________________________                                        Composition A           5.0 grams                                             Bis(2-o-chlorophenyl-4,5-                                                                             0.3 grams                                             diphenylimidazolyl)                                                           Michler's ketone (tetramethyl                                                                         0.15 grams                                            diaminobenzophenone)                                                          Tris(diethylamino-o-tolyl) methane                                                                    0.10 grams                                            Tetraethylene glycol diacrylate                                                                       0.75 grams                                            N--methylpyrrolidone    9.70 grams                                            Ethylene glycol monoethyl ether                                                                       1.70 grams                                            ______________________________________                                    

The above Composition B was filtered through a 1 micrometer filter.

A 2-inch diameter silicon wafer was coated with an aminosilane adhesionpromoter solution by a spin coating technique wherein the wafer wasrotated at 3000 rpm for 30 seconds after the adhesion promoter solutionwas applied.

Then, Composition B was applied to the wafer by the above spin techniqueusing 3000 rpm for 60 seconds. This wafer with a coating of CompositionB was then dried for 2 hours at 50° C., after which it was exposed to anultraviolet light source of 365 nanometers (nm) and an intensity ofabout 5 mW/cm², said light passing through a masking template.

The wafer was then developed by dipping it for 20 seconds in a 1/1solution of 4-butyrolactone/toluene and then rinsing it for 10 secondswith a spray of toluene to remove any unexposed composition. The waferwas then spun dry at 3000 rpm for 60 seconds. The wafer was, finally,heated and held at about 300° C. for 1 hour to provide a polyimiderelief structure of an electronic circuit, which is characterized bysharp, clean lines.

I claim:
 1. A radiation-sensitive polyimide precursor composition,comprising:a. a polymer of the formula ##STR9## wherein n is a positiveinteger corresponding to the number of units in the polymer and issufficiently large to provide the polymer with a number averagemolecular weight of about 1500-15,000 as determined by vapor pressureosmometry, and wherein for any particular unit in the polymer: → denotesisomerism;R¹ is a tetravalent, aromatic, non-halogen containing, organicradical containing at least one ring of six carbon atoms, said ringcharacterized by benzenoid unsaturation, the four carbonyl groups beingattached directly to separate carbon atoms in a ring of the R¹ radical;R² and R³ are selected from the group consisting of a hydrogen radicaland any organic radical containing a photopolymerizable olefinic doublebond, at least one of R² and R³ being said organic radical; R⁴ and R⁵are selected from the group consisting of perfluoro and perhalofluoroaliphatic hydrocarbons having 1 to 8 carbons; and A and A' are selectedfrom the group consisting of H, Cl, Br, and NO₂ ; b. aradiation-sensitive polymerizable polyfunctional acrylate compound; andc. a photopolymerization initiator system comprising hydrogen donorinitiator and aromatic biimidazole.
 2. A radiation-sensitive polyimideprecursor composition as recited in claim 1 wherein R⁴ and R⁵ areselected from the group consisting of --CF₃, --CClF₂, and --CBrF₂.
 3. Aradiation-sensitive polyimide precursor composition as recited in claim2 wherein R² and R³ are selected from the group consisting of a hydrogenradical, a hydroxy alkyl acrylate radical, and a hydroxy alkylmethacrylate radical.
 4. A radiation-sensitive polyimide precursorcomposition as recited in claim 2 wherein R² and R³ are selected fromthe group consisting of a hydrogen radical, an alkyl acrylate radical,and an alkyl methacrylate radical.
 5. A radiation-sensitive polyimideprecursor composition as recited in claims 1, 2, 3 or 4 wherein:a. theradiation-sensitive polymerizable polyfunctional acrylate compound ispresent in an amount equal to 5-30% by weight of the polymer; and b. thephotopolymerization initiator system is present in an amount equal to0.5-30% by weight of the polymer.
 6. A radiation-sensitive polyimideprecursor composition, as recited in claim 5, wherein said radiationsensitive polymerizable polyfunctional acrylate compound is selectedfrom the group consisting of trimethylol propane trimethacrylate,trimethylol propane triacrylate, trimethylol propane ethoxylatetrimethacrylate, trimethylol propane ethoxylate triacrylate, trimethylolpropane polyethoxylate trimethacrylate, trimethylol propanepolyethoxylate triacrylate, penterythritol triacrylate, polyethyleneglycol diacrylate, triethylene glycol diacrylate, polyethylene glycoldimethacrylate, polymethylene diacrylate, polymethylene dimethacrylate,trimethylene glycol dimethacrylate, tetraethylene glycol diacrylate, andmixtures thereof.
 7. A radiation-sensitive polyimide precursorcomposition, as recited in claim 6, in which said aromatic biimidazoleof said photopolymerization initiator is selected from the groupconsisting of bis(2-o-chlorophenyl-4,5-diphenyl and imidazolyl) andbis[2-o-chlorophenyl-4,5-di(m-methoxyphenol)imidazolyl].
 8. Aradiation-sensitive polyimide precursor composition, as recited in claim7, wherein the composition also contains about 0.1-10% by weight, basedon the weight of the polymer, of a leuco dye.
 9. A radiation-sensitivepolyimide precursor composition, as recited in claim 8, wherein thecomposition also contains about 0.1-15% by weight, based on the weightof the polymer of a photosensitizer.
 10. A method for the preparation ofa radiation-sensitive polyimide precursor composition, as recited inclaim 1, comprising:a. reacting a tetracarboxylic acid dianhydride ofthe formula ##STR10## wherein R¹ is a tetravelent, aromatic, non-halogencontaining, organic radical containing at least one ring of six carbonatoms, said ring characterized by benzenoid unsaturation, the fourcarbonyl groups being attached directly to separate carbon atoms in aring of the R¹ radical with at least one organic diamine of the formula##STR11## wherein R⁴ and R⁵ are selected from the group consisting ofperfluoro and perhalofluoro aliphatic hydrocarbons having 1 to 8carbons; andA and A' are selected from the group consisting of H, Cl,Br, and NO₂ ; in a suitable solvent at a temperature below about 75° C.to form a carboxyl group-containing reaction product; b. reacting saidreaction product with an olefinically unsaturated monoepoxide at atemperature from about room temperature to about 100° C. in an organicsolvent to form an addition product; c. adding to a solution of saidaddition product, a radiation-sensitive polymerizable polyfunctionalacrylate compound; and d. also adding to said solution aphotopolymeriation initiator system comprising hydrogen donor initiatorand aromatic biimidazole.
 11. A method as recited in claim 10 wherein R⁴and R⁵ are selected from the group consisting of --CF₃, --CClF₂, and--CBrF₂.
 12. A method as recited in claim 10 wherein the reactionproduct of the dianhydride and the diamine is brought to reaction with acompound from the group consisting of hydroxyethyl acrylate,hydroxyethyl methacrylate, and a combination of the two, prior to thereaction with said olefinically unsaturated monoepoxide.
 13. A methodfor the preparation of a radiation-sensitive polyimide precursorcomposition, as recited in claim 1, comprising:a. reacting atetracarboxylic acid dianhydride of the formula ##STR12## wherein R¹ isas recited in claim 1, with a compound selected from the groupconsisting of hydroxy alkyl acrylates and hydroxy alkyl methacrylates toform an esterification product; b. forming an acid chloride derivativeof said esterification product; c. reacting said acid chloridederivative with a diamine of the formula ##STR13## wherein R⁴, R⁵, A,and A' are as recited in claim 1, to form an addition product; d. addingto a solution of said addition product, a radiation-sensitivepolymerizable polyfunctional acrylate compound; and e. also adding tosaid solution a photopolymerization initiator system comprising hydrogendonor initiator and aromatic biimidazole.
 14. A method as recited inclaim 13 wherein R⁴ and R⁵ are selected from the group consisting of--CF₃, --CClF₂, and --CBrF₂.